TY  - JOUR
AU  - Castro,  Alfonso
AU  - Cossio,  Jorge
AU  - Neuberger,  John M.
TI  - A minimax principle, index of the critical point, and existence of sign-changing solutions to elliptic boundary value problems
JO  - Electronic journal of differential equations
PY  - 1998
VL  - 1998
UR  - http://geodesic.mathdoc.fr/item/EJDE_1998__1998__a13/
LA  - en
ID  - EJDE_1998__1998__a13
ER  -